Backlash estimation method, program, and backlash estimation device

Abstract

The present invention provides a backlash estimation method, program, and backlash estimation device that can estimate the amount of backlash with high accuracy without the need to install a separate sensor. [Solution] The backlash estimation method estimates the amount of backlash between a drive gear and a driven gear. The backlash estimation method includes a motor drive step of driving a motor to rotate the drive gear from the first side to the second side, then reversing the direction of rotation of the drive gear, and rotating the drive gear from the second side to the first side; a torque acquisition step of acquiring the torque of the motor during the reversal period of rotation of the drive gear; a backlash time estimation step of estimating the backlash time required for the drive teeth of the drive gear to move through the backlash based on the torque of the motor; and a backlash amount estimation step of estimating the product of the backlash time and the rotational speed of the drive gear as the amount of backlash.

Description

Technical Field

[0003]

[0001] The present disclosure relates to a backlash estimation method, a program, and a backlash estimation device.

Background Art

[0002] Gear wear is generally evaluated qualitatively. However, in qualitative wear evaluation, the exact wear amount is not measured, and when the wear amount is small, the accuracy of wear evaluation decreases.

[0003] When performing wear evaluation quantitatively, it is necessary to add a plurality of sensors such as rotary encoders. For example, in the monitoring method of Patent Document 1, sensors for detecting the angular position are provided on each of the shafts of two meshing gears. The angular positions of the two shafts are detected by these sensors. Then, the wear of the gearbox is monitored according to the difference in the angular positions of the two shafts.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as the gear wears, the backlash amount between two meshing gears increases. That is, the wear amount is taken into account in the backlash amount. Therefore, wear can be evaluated quantitatively by estimating the backlash amount. However, even when estimating the backlash amount, it was necessary to separately provide a sensor such as a rotary encoder.

[0006] This disclosure was made to solve the above problems and aims to provide a backlash estimation method, program, and backlash estimation device that can estimate the amount of backlash with high accuracy without installing a separate sensor. [Means for solving the problem]

[0007] To solve the above problems, the backlash estimation method according to the present disclosure is a backlash estimation method for estimating the amount of backlash between a drive gear driven by a motor and a driven gear meshing with the drive gear, and includes: a motor driving step of driving the motor to rotate the drive gear in a direction from a first side to a second side, then reversing the direction of rotation of the drive gear, so that the drive gear rotates in a direction from the second side to the first side; a torque acquisition step of acquiring the torque of the motor during the reversal period in which the direction of rotation of the drive gear is reversed; a backlash time estimation step of estimating the backlash time required for the drive teeth of the drive gear to move from an initial position in contact with the driven teeth of the driven gear located on the second side to an final position in contact with the driven teeth located on the first side, based on the torque of the motor during the reversal period; and a backlash amount estimation step of estimating the product of the backlash time estimated in the backlash time estimation step and the rotational speed of the drive gear as the amount of backlash.

[0008] The program relating to this disclosure is a program for estimating the amount of backlash between a drive gear driven by a motor and a driven gear meshing with the drive gear, and causes a computer to execute the following: a motor drive step of driving the motor to rotate the drive gear in a direction from a first side to a second side, then reversing the direction of rotation of the drive gear, so that the drive gear rotates in a direction from the second side to the first side; a torque acquisition step of acquiring the torque of the motor during the reversal period in which the direction of rotation of the drive gear is reversed; a backlash time estimation step of estimating the backlash time required for the drive teeth of the drive gear to move from an initial position in contact with the driven teeth of the driven gear located on the second side to an final position in contact with the driven teeth located on the first side, based on the torque of the motor during the reversal period; and a backlash amount estimation step of estimating the product of the backlash time estimated in the backlash time estimation step and the rotational speed of the drive gear as the amount of backlash.

[0009] The backlash estimation device according to this disclosure is a backlash estimation device for estimating the amount of backlash between a drive gear driven by a motor and a driven gear meshing with the drive gear, comprising: a motor drive unit that rotates the drive gear in a direction from a first side to a second side, then reverses the direction of rotation of the drive gear and drives the motor to rotate the drive gear in a direction from the second side to the first side; a torque acquisition unit that acquires the torque of the motor during the reversal period in which the direction of rotation of the drive gear is reversed; a backlash time estimation unit that estimates the backlash time required for the drive teeth of the drive gear to move from an initial position in contact with the driven teeth of the driven gear located on the second side to an final position in contact with the driven teeth located on the first side, based on the torque of the motor during the reversal period; and a backlash amount estimation unit that estimates the product of the backlash time estimated by the backlash time estimation unit and the rotational speed of the drive gear as the amount of backlash. [Effects of the Invention]

[0010] According to the backlash estimation method, program, and backlash estimation device of this disclosure, the amount of backlash can be estimated with high accuracy without the need to separately install a sensor. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a gear mechanism according to an embodiment of the present disclosure. [Figure 2] This is an enlarged view of the meshing portion between the drive gear and the driven gear according to the embodiment of this disclosure. [Figure 3] This is a schematic diagram illustrating a method for estimating the amount of backlash according to the embodiments of this disclosure. [Figure 4] This graph illustrates a method for estimating the amount of backlash according to the embodiments of this disclosure. [Figure 5] This is a functional block diagram of an example of a backlash estimation device according to the present disclosure. [Figure 6] This flowchart shows an example of the procedure for the backlash estimation method according to the embodiment of this disclosure. [Figure 7] This flowchart shows an example of the procedure for the backlash time estimation process according to the embodiment of this disclosure. [Figure 8] This is an example of the data used in the backlash estimation method according to the embodiment of this disclosure. [Figure 9] This graph shows data obtained by removing low-frequency noise from torque data according to the embodiments of this disclosure. [Figure 10] This graph shows data obtained by removing low-frequency noise from the time rate of change data of torque according to the embodiment of this disclosure. [Figure 11] This is a hardware configuration diagram according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] Hereinafter, the backlash estimation method and the backlash estimation device 30 according to the present embodiment will be described with reference to FIGS. 1 to 10. The backlash estimation method and the backlash estimation device 30 of the present embodiment are applied to, for example, the gear mechanism 1 shown in FIG. 1.

[0013] (Configuration of Gear Mechanism) The gear mechanism 1 is a gearbox applied to, for example, a speed increasing unit of a wind power generator or a speed reducer of a vehicle. The gear mechanism 1 includes a driving gear 10, a driven gear 20, a motor 2, and a backlash estimation device 30.

[0014] The driving gear 10 is connected to the motor 2 via a shaft (not shown). The driving gear 10 is driven by the torque of the motor 2. The driving gear 10 has a driving gear main body 11 and driving teeth 12. The driving gear main body 11 is formed in a disk shape. A plurality of driving teeth 12 are formed on the entire outer peripheral edge of the driving gear main body 11. The plurality of driving teeth 12 are provided at equal intervals in the circumferential direction of the driving gear main body 11. Each driving tooth 12 protrudes radially outward from the outer peripheral edge of the driving gear main body 11. All the driving teeth 12 are formed in the same shape.

[0015] The driven gear 20 is provided so as to mesh with the driving gear 10. The driven gear 20 rotates when the torque of the motor 2 is transmitted by the driving gear 10. The driven gear 20 has a driven gear main body 21 and driven teeth 22. The driven gear main body 21 is formed in a disk shape. A plurality of driven teeth 22 are formed on the entire outer peripheral edge of the driven gear main body 21. The plurality of driven teeth 22 are provided at equal intervals in the circumferential direction of the driven gear main body 21. Each driven tooth 22 protrudes radially outward from the outer peripheral edge of the driven gear main body 21. All the driven teeth 22 are formed in the same shape. At the portion where the driving gear 10 and the driven gear 20 mesh, as shown in FIG. 2, the driving gear 10 is disposed between two driven teeth 22.

[0016] A clearance called backlash is formed in advance between these drive gear 10 and driven gear 20. The backlash here refers to the area between the drive gear 10 and the driven gear 20 at the meshing part of the drive gear 10 and the driven gear 20. The backlash absorbs thermal expansion between gears and misalignment between gears. Hereinafter, the length of the backlash in the circumferential direction (rotation direction Dr) is referred to as the backlash amount Lb. When the drive gear 10 and the driven gear 20 wear and the wear amount increases, the backlash amount Lb increases. That is, the backlash amount Lb is a value obtained by adding the wear amount to the initial backlash amount Lb before wear. Therefore, by estimating the backlash amount Lb, it becomes possible to quantitatively evaluate the wear amount. Hereinafter, a backlash estimation device 30 and a backlash estimation method for estimating the backlash amount Lb between such a drive gear 10 and a driven gear 20 will be described.

[0017] (Backlash Estimation Device) The backlash estimation device 30 is electrically connected to the motor 2. The backlash estimation device 30 estimates the backlash amount Lb based on the torque data of the motor 2. Hereinafter, the main part of the method for backlash estimation according to the present embodiment will be described. Hereinafter, the rotation direction Dr of the drive gear 10 is simply referred to as the rotation direction Dr. This rotation direction Dr coincides with the circumferential direction of the drive gear 10. One side of the rotation direction Dr is referred to as the first side Dr1, and the other side of the rotation direction Dr is referred to as the second side Dr2.

[0018] As shown in FIG. 3, the backlash estimation device 30 rotates the drive gear 10 at a rotational speed vb in the direction from the first side Dr1 to the second side Dr2. At this time, the backlash estimation device 30 rotates the drive gear 10 at a lower speed compared to when the drive gear 10 is normally driven. The backlash estimation device 30 rotates the drive gear 10 until the drive tooth 12 sandwiched between the two driven teeth 22 abuts against the driven tooth 22 on the second side Dr2 at the meshing part of the drive gear 10 and the driven gear 20. The position of the drive tooth 12 at the time of abutting against the driven tooth 22 on the second side Dr2 is referred to as the initial position A1.

[0019] Subsequently, the backlash estimation device 30 reverses the rotation direction Dr of the drive gear 10 and rotates the drive gear 10 at a rotation speed vb in the direction from the second side Dr2 to the first side Dr1. The rotation speed vb of the drive gear 10 at this time is approximately the same as the rotation speed vb of the drive gear 10 before the reversal. The backlash estimation device 30 rotates the drive gear 10 until the drive teeth 12 at the initial position A1 come into contact with the driven teeth 22 of the first side Dr1. The position of the drive teeth 12 at the time of contact with the driven teeth 22 of the first side Dr1 is referred to as the final position A2.

[0020] The distance the drive teeth 12 travel from the initial position A1 to the final position A2 is considered to be the backlash amount Lb. The backlash estimation device 30 calculates the time it takes for the drive teeth 12 to move from the initial position A1 to the final position A2 as the backlash time tb. The backlash estimation device 30 then calculates the product of the backlash time tb and the drive teeth 12 as the backlash amount Lb. In this embodiment, the backlash time tb is estimated based on the time change of the torque of the motor 2. The main part of the method for estimating the backlash time tb based on the torque of the motor 2 will be described below.

[0021] Hereinafter, the period during which the rotation direction Dr of the drive gear 10 reverses will be referred to as the reversal period tr. This reversal period tr may include a predetermined period before the rotation of the motor 2 reverses, and a predetermined period after the rotation direction Dr reverses and the drive teeth 12 moves from the initial position A1 to the final position A2.

[0022] The backlash estimation device 30 acquires the torque of motor 2 shown in Figure 4. Figure 4 shows a graph of the torque of motor 2 (lower side) as well as a graph of the input signal controlling the rotation angle of motor 2 (upper side). In the input signal graph, the horizontal axis represents time, and the vertical axis represents the input value of the rotation angle of motor 2. The vertical axis may also represent the input position of the rotational position of motor 2. The lower graph in Figure 4 is the torque graph of motor 2. In the motor 2 torque graph, the horizontal axis represents time, and the vertical axis represents the torque of motor 2. In the following explanation, the direction, displacement, and torque from the second side Dr2 to the first side Dr1 are considered positive.

[0023] The method for measuring the torque of motor 2 can be selected as appropriate. For example, the torque of motor 2 may be obtained by a rotational torque sensor pre-installed on the gear mechanism 1. The torque of motor 2 is proportional to the current value of motor 2. Therefore, the torque of motor 2 may be obtained by calculating it based on the current value of motor 2, which is proportional to the torque.

[0024] When the rotation of motor 2 begins to reverse, the drive teeth 12, which are in their initial position A1, separate from the driven teeth 22 of the second side Dr2. At this time, the drive gear 10 is subjected to a force in the opposite direction to the direction from the second side Dr2 to the first side Dr1 due to resistance such as the weight of the drive gear 10 and friction with the driven gear 20, and the torque of motor 2 increases rapidly (times t0 to t1 in Figure 4). Hereafter, when the rotation direction Dr of motor 2 is reversed in this manner, the time when the torque first changes rapidly will be called the rapid change time tr1. The rapid change time tr1 is included in the reversal period tr. When the drive teeth 12 are completely separated from the driven teeth 22, the resistance on the drive gear 10 becomes almost constant. As a result, the torque of motor 2 remains stable and almost constant compared to the rapid change time tr1 until the drive teeth 12 contact the driven teeth 22 of the first side Dr1 (times t1 to t2 in Figure 4). The backlash estimation device 30 calculates the time from time t1 to time t2, when the torque is stable, as the backlash time tb.

[0025] (An example of a backlash estimation device) Next, we will describe an example of the functional configuration of the backlash estimation device 30. The backlash estimation device 30 has the following functional units: a motor drive unit 31, a torque acquisition unit 32, a backlash time estimation unit 40, a backlash amount estimation unit 33, and a wear amount estimation unit 34.

[0026] (Motor drive unit) The motor drive unit 31 receives a control signal and drives the motor 2 to rotate in an arbitrary direction at an arbitrary rotational speed vb. The motor drive unit 31 can also determine the rotational direction of the motor 2. The control signal input to the motor 2 for driving the motor 2 is predetermined.

[0027] (Torque acquisition unit) The torque acquisition unit 32 acquires torque data output from the motor 2 for a predetermined period (see the first row of Figure 8). More specifically, the torque acquisition unit 32 acquires the torque of the motor 2 during a period that includes the reversal period tr in which the rotation direction of the drive gear 10 reverses.

[0028] (Backlash time estimation unit) The backlash time estimation unit 40 estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from the initial position A1 (see Figure 3) to the final position A2 (see Figure 3) based on the torque of the motor 2 during the reversal period tr. More specifically, the backlash time estimation unit 40 estimates the time when the torque of the motor 2 stabilizes immediately after the abrupt change time tr1 in which the torque of the motor 2 changes rapidly during the reversal period tr as the backlash time tb (see the third and fifth stages of Figure 8). The backlash time estimation unit 40 of this embodiment has the following functional units: a first filter unit 41, a torque time change rate acquisition unit 42, a second filter unit 43, a peak detection unit 44, and a backlash time calculation unit 45.

[0029] (First filter section) The first filter unit 41 removes predetermined low-frequency noise from the torque acquired by the torque acquisition unit 32.

[0030] (Torque Time Change Rate Acquisition Unit) The torque time change rate acquisition unit 42 acquires the time change rate of the torque at each time point by differentiating the torque acquired by the torque acquisition unit 32 and after noise has been removed by the first filter unit 41.

[0031] (Second filter section) The second filter unit 43 removes predetermined low-frequency noise from the torque time rate change rate acquired by the torque time rate change rate acquisition unit 42.

[0032] (Peak detection unit) The peak detection unit 44 detects the first peak within the reversal period tr in the torque time rate graph, which is acquired by the torque time rate acquisition unit 42 and after noise has been removed by the second filter unit 43, as the first peak P1 (see the fourth row in Figure 8), and detects the first peak after the occurrence of the first peak P1 within the reversal period tr as the second peak P2 (see the fourth row in Figure 8).

[0033] (Backlash time calculation unit) The backlash time calculation unit 45 calculates the backlash time tb by setting the time of the first peak P1 or the time immediately following the first peak P1 as the start time tb1 of the backlash time tb, and the time of the second peak P2 or the time immediately following the second peak P2 as the end time tb2 of the backlash time tb.

[0034] (Backlash amount estimation unit) The backlash amount estimation unit 33 estimates the backlash amount Lb as the product of the backlash time tb estimated by the backlash time estimation unit 40 and the rotational speed vb of the drive gear 10.

[0035] (Wear amount estimation unit) The wear amount estimation unit 34 estimates the wear amount based on the backlash amount Lb estimated by the backlash amount estimation unit 33.

[0036] (Procedure for estimating backlash) Next, an example of the backlash estimation procedure will be explained with reference to the flowcharts in Figures 6 and 7 and the data in Figures 8 to 10. As shown in Figure 6, the backlash estimation method includes a motor drive step S1, a torque acquisition step S2, a backlash time estimation step S3, a backlash amount estimation step S4, and a wear amount estimation step S5.

[0037] First, the motor drive process S1 is performed. In the motor drive process S1, the motor drive unit 31 rotates the drive gear 10 in the direction from the first side Dr1 to the second side Dr2, then reverses the rotation direction Dr of the drive gear 10 and drives the motor 2 to rotate the drive gear 10 in the direction from the second side Dr2 to the first side Dr1 (see Figure 3). In this embodiment, the motor 2 is driven to rotate the drive gear 10 alternately in the direction from the first side Dr1 to the second side Dr2 and in the direction from the second side Dr2 to the first side Dr1.

[0038] After the motor 2 starts to drive, a torque acquisition process S2 is performed. In the torque acquisition process S2, the torque acquisition unit 32 acquires the torque of the motor 2 during a period that includes a reversal period tr in which the rotation direction Dr of the drive gear 10 reverses. This allows the time change of torque to be acquired, for example, as shown in the first to third rows of the graph in Figure 8. In the first to third rows of the graph in Figure 8, the horizontal axis represents time, and the vertical axis represents the torque of the motor 2. The direction, displacement, and torque from the second side Dr2 to the first side Dr1 are described as positive. The second row of the graph in Figure 8 is an enlarged view of the reversal period tr (around 144s) in the first row of the graph in Figure 8. The third row of the graph in Figure 8 is a further enlarged view of the reversal period tr (around 144s) in the second row of the graph in Figure 8. As shown in the third row of Figure 8, just before 144s, the torque of the motor 2 increases sharply (sudden change time tr1). This occurs when the motor 2 begins to reverse its rotation, and the drive teeth 12, which are in their initial position A1, separate from the driven teeth 22 of the second side Dr2. At this point, the drive gear 10 is subjected to a force in the opposite direction to the direction from the second side Dr2 to the first side Dr1 due to resistance forces such as the weight of the drive gear 10 and friction with the driven gear 20. To counteract this resistance force in the opposite direction, the torque of the motor 2 increases rapidly. Subsequently, from the time the drive teeth 12 completely separate from the driven teeth 22 of the second side Dr2 and contact the driven teeth 22 of the first side Dr1, the resistance force on the drive gear 10 hardly changes, so the torque of the motor 2 stabilizes and becomes approximately constant. A procedure to identify the time when the torque of the motor 2 stabilizes and estimate it as the backlash time tb is performed from the torque acquisition process S2 onward.

[0039] After the torque acquisition step S2, the backlash time estimation step S3 is performed. In the backlash time estimation step S3, the backlash time estimation unit 40 estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from the initial position A1 (see Figure 3) to the final position A2 (see Figure 3) based on the torque of the motor 2 during the reversal period tr. An example of the procedure for the backlash time estimation step S3 in this embodiment will be described in detail below. In this embodiment, the backlash time estimation step S3 includes a first filter step S10, a torque time change rate acquisition step S11, a second filter step S12, a peak detection step S13, and a backlash time calculation step S14.

[0040] First, the first filtering process S10 is performed. In the first filtering process S10, the first filter unit 41 removes predetermined low-frequency noise from the torque acquired in the torque acquisition process S2. As a result, noise is removed from the graph shown in the third row of Figure 8, and the graph shown in Figure 9 is obtained.

[0041] After the first filtering process S10, the torque time rate of change acquisition process S11 is performed. In the torque time rate of change acquisition process S11, the torque time rate of change acquisition unit 42 acquires the time rate of change of torque at each time point by differentiating the torque acquired in the torque acquisition process S2 and from which noise has been removed in the first filtering process S10. This yields the graph shown in the fourth row of Figure 8.

[0042] After the torque time rate of change acquisition process S11, the second filtering process S12 is performed. In the second filtering process S12, the second filter unit 43 removes predetermined low-frequency noise from the torque time rate of change acquired in the torque time rate of change acquisition process S11.

[0043] After the second filtering process S12, the peak detection process S13 is performed. In the peak detection process S13, the peak detection unit 44 detects the first peak within the reversal period tr in the torque time rate change graph acquired in the torque time rate change acquisition process S11 and from which noise has been removed in the second filtering process S12 as the first peak P1, and detects the first peak after the occurrence of the first peak P1 within the reversal period tr as the second peak P2.

[0044] After the peak detection step S13, the backlash time calculation step S14 is performed. In the backlash time calculation step S14, the backlash time calculation unit 45 calculates the backlash time tb based on the first peak P1 and the second peak P2. Specifically, the backlash time calculation unit 45 sets the time of the first peak P1 or the time immediately following the first peak P1 as the start time tb1 of the backlash time tb. The backlash time calculation unit 45 also sets the time of the second peak P2 or the time immediately following the second peak P2 as the end time tb2 of the backlash time tb. More specifically, the backlash time calculation unit 45 sets the time immediately following the first peak P1 when the rate of change of torque over time becomes zero as the start time tb1 of the backlash time tb. The backlash time calculation unit 45 also sets the time immediately following the second peak P2 when the rate of change of torque over time becomes zero as the end time tb2 of the backlash time tb. The time from the start time tb1 to the end time tb2, as determined in this way, becomes the backlash time tb.

[0045] The backlash time estimation process S3 is completed using the above procedure. After the backlash time estimation process S3, the backlash amount estimation process S4 is performed. In the backlash amount estimation process S4, the backlash amount estimation unit 33 estimates the backlash amount Lb as the product of the backlash time tb estimated in the backlash time estimation process S3 and the rotational speed vb of the drive gear 10. That is, the backlash amount Lb is calculated by the following equation (1). (Backlash amount Lb) = (Backlash time tb) * (Rotational speed vb) ... (1)

[0046] After the backlash amount estimation step S4, the wear amount estimation step S5 is performed. In the wear amount estimation step S5, the wear amount estimation unit 34 estimates the wear amount based on the backlash amount Lb estimated in the backlash amount estimation step S4. For example, the wear amount estimation unit 34 estimates the current wear amount by subtracting the backlash amount Lb before wear from the current backlash amount Lb estimated in the backlash amount estimation step S4.

[0047] The backlash estimation method is completed using the above procedure. Alternatively, the backlash time tb may be calculated over multiple reversal periods tr using the procedure described above, and the average or median of these multiple backlash times tb may be used as the estimated value of the backlash time tb. Or, the backlash amount Lb may be calculated over multiple reversal periods tr using the procedure described above, and the average or median of these amounts may be used as the backlash amount Lb. Furthermore, the series of steps in the backlash estimation method described above may be performed periodically at regular intervals (hourly, daily, weekly, or yearly).

[0048] (Effects and Benefits) According to the above embodiment, the following effects and advantages can be achieved.

[0049] The backlash estimation method of this embodiment includes a motor drive step S1, a torque acquisition step S2, a backlash time estimation step S3, and a backlash amount estimation step S4. In the motor drive step S1, the motor drive unit 31 rotates the drive gear 10 in the direction from the first side Dr1 to the second side Dr2, then reverses the rotation direction Dr of the drive gear 10 and drives the motor 2 to rotate the drive gear 10 in the direction from the second side Dr2 to the first side Dr1. In the torque acquisition step S2, the torque acquisition unit 32 acquires the torque of the motor 2 during the reversal period tr in which the rotation direction Dr of the drive gear 10 is reversed. In the backlash time estimation step S3, the backlash time estimation unit 40 estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from the initial position A1, where it contacts the driven teeth 22 of the driven gear 20 located on the second side Dr2, to the final position A2, based on the torque of the motor 2 during the reversal period tr. In the backlash amount estimation step S4, the backlash amount estimation unit 33 estimates the backlash amount Lb as the product of the backlash time tb estimated in the backlash time estimation step S3 and the rotational speed vb of the drive gear 10.

[0050] When the rotation of motor 2 reverses and the drive teeth 12 move from an initial position A1 where they contact the driven teeth 22 of the first side Dr1 to an end position A2 where they contact the driven teeth 22 of the second side Dr2, the torque of motor 2 fluctuates in a special waveform. According to this embodiment, based on this special fluctuation of the torque of motor 2, the backlash time tb required for the drive teeth 12 to move from the initial position A1 to the end position A2 can be estimated. The product of the backlash time tb and the rotational speed vb of the drive gear 10 can then be estimated as the amount of backlash Lb between the drive gear 10 and the driven gear 20. Therefore, the amount of backlash Lb can be estimated with high accuracy without separately installing sensors such as a rotary encoder.

[0051] In this embodiment, the reversal period tr includes a sudden change time tr1 in which the torque of motor 2 changes rapidly. In the backlash time estimation step S3, the backlash time estimation unit 40 estimates the time immediately after this sudden change time tr1 in which the torque of motor 2 stabilizes as the backlash time tb.

[0052] During the time that the drive teeth 12 move from the initial position A1 to the final position A2, the resistance such as friction on the drive gear 10 decreases, and the torque of the motor 2 stabilizes. According to this embodiment, by estimating the time during which the torque of the motor 2 stabilizes as the backlash time tb, the backlash time tb can be easily estimated. This makes it possible to easily estimate the amount of backlash Lb.

[0053] In this embodiment, the backlash time estimation step S3 includes a torque time rate change acquisition step S11, a peak detection step S13, and a backlash time calculation step S14. In the torque time rate change acquisition step S11, the torque time rate change acquisition unit 42 acquires the time rate change of torque at each time by differentiating the torque acquired in the torque acquisition step S2 with respect to time. In the peak detection step S13, the peak detection unit 44 detects the first peak within the reversal period tr in the graph of the time rate change of torque acquired in the torque time rate change acquisition step S11 as the first peak P1, and detects the first peak after the occurrence of the first peak P1 within the reversal period tr as the second peak P2. In the backlash time calculation step S14, the backlash time calculation unit 45 calculates the backlash time tb by setting the time of the first peak P1 or the time immediately following the first peak P1 as the start time tb1 of the backlash time tb, and the time of the second peak P2 or the time immediately following the second peak P2 as the end time tb2 of the backlash time tb.

[0054] According to this embodiment, the time during which torque is stable can be calculated with high accuracy. Therefore, the backlash time tb can be calculated with high accuracy. As a result, the amount of backlash Lb can be estimated with even higher accuracy based on the backlash time tb.

[0055] In this embodiment, the backlash time estimation step S3 further includes a first filtering step S10 before the torque time change rate acquisition step S11. In the first filtering step S10, the first filter unit 41 removes predetermined low-frequency noise from the torque acquired in the torque acquisition step S2.

[0056] This allows for the calculation of the torque rate of change over time by removing noise from the torque measurement. Therefore, the backlash time tb can be estimated with high accuracy based on the graph of the torque rate of change over time. Consequently, the amount of backlash Lb can be estimated with even higher accuracy based on the backlash time tb.

[0057] In this embodiment, the backlash time estimation step S3 further includes a second filtering step S12 after the peak detection step S13. In the second filtering step S12, the second filtering unit 43 removes predetermined low-frequency noise from the torque time rate change acquired in the torque time rate change acquisition step S11.

[0058] According to this embodiment, noise can be removed from the rate of change of torque over time. This makes the first peak P1 and the second peak P2 clear. Therefore, the backlash time tb present between the first peak P1 and the second peak P2 can be estimated with high accuracy. Consequently, the amount of backlash Lb can be estimated with even higher accuracy based on the backlash time tb.

[0059] In this embodiment, the backlash time calculation step S14 calculates the backlash time tb by setting the start time tb1 as the time when the rate of change of torque becomes 0 for the first time immediately after the first peak P1, and the end time tb2 as the time when the rate of change of torque becomes 0 immediately before the second peak P2.

[0060] This clarifies the start time tb1 and end time tb2 of the backlash time tb. Therefore, the backlash time tb can be estimated more easily and with higher accuracy. Consequently, the amount of backlash Lb can be estimated more easily and with higher accuracy based on the backlash time tb.

[0061] The backlash estimation method of this embodiment further includes a wear amount estimation step S5. In the wear amount estimation step S5, the wear amount estimation unit estimates the wear amount based on the backlash amount Lb estimated in the backlash amount estimation step S4.

[0062] The backlash amount Lb includes the amount of wear between the drive gear 10 and the driven gear 20 in addition to the backlash amount Lb before wear. In other words, the backlash amount Lb increases as the amount of wear increases. Therefore, according to this embodiment, the amount of wear can be easily estimated based on the estimated value of the backlash amount Lb. Thus, the quantitative evaluation of wear between the drive gear 10 and the driven gear 20 can be performed with high accuracy.

[0063] <Hardware Configuration> The backlash estimation device 30 of the above embodiments and modified examples is implemented in the computer 1100 shown in Figure 11. Figure 11 is a schematic block diagram showing the configuration of the computer 1100 according to each embodiment. The computer 1100 includes a processor 1110, main memory 1120, storage 1130, and interface 1140.

[0064] The operation of each of the above-mentioned functional units of the backlash estimation device 30 is stored in the storage 1130 in the form of a program. The processor 1110 reads the program from the storage 1130, loads it into the main memory 1120, and executes the above-mentioned process according to the program. The processor 1110 also allocates storage space in the main memory 1120 according to the program.

[0065] The program may be for the purpose of realizing some of the functions that the computer 1100 is to perform. For example, the program may perform functions in combination with other programs already stored in the storage 1130, or in combination with other programs implemented in other devices. In addition, the computer 1100 may be equipped with a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 1110 may be realized by the integrated circuit.

[0066] Examples of storage 1130 include magnetic disks, magneto-optical disks, and semiconductor memory. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line. Furthermore, if this program is distributed to computer 1100 via a communication line, computer 1100 that receives the program may expand it into main memory 1120 and execute the above processing. Storage 1130 may also be a tangible storage medium that is not temporary.

[0067] Furthermore, the program may be intended to implement some of the functions described above. In addition, the program may be a so-called differential file (differential program) that implements the functions described above in combination with other programs already stored in the storage 1130.

[0068] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure.

[0069] For example, in this embodiment, the backlash time estimation process is described as including a first filter process and a second filter process, but it is not limited to this. The first filter process and the second filter process may be omitted.

[0070] <Note> The backlash estimation method, program, and backlash estimation system described in each embodiment can be understood, for example, as follows.

[0071] (1) A backlash estimation method according to the first embodiment is a backlash estimation method for estimating the amount of backlash Lb between a drive gear 10 driven by a motor 2 and a driven gear 20 that meshes with the drive gear 10, comprising: a motor drive step S1 in which the motor 2 is driven to rotate the drive gear 10 in the direction from the first side Dr1 to the second side Dr2, then reverses the rotation direction Dr of the drive gear 10 and rotates the drive gear 10 in the direction from the second side Dr2 to the first side Dr1; and a step S1 in which the torque of the motor 2 is obtained during the reversal period tr in which the rotation direction Dr of the drive gear 10 is reversed. The process includes: a torque acquisition step S2; a backlash time estimation step S3 which estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from an initial position A1 where it contacts the driven teeth 22 of the driven gear 20 located on the second side Dr2 to an end position A2 where it contacts the driven teeth 22 located on the first side Dr1, based on the torque of the motor 2 during the reversal period tr; and a backlash amount estimation step S4 which estimates the product of the backlash time tb estimated in the backlash time estimation step S3 and the rotational speed vb of the drive gear 10 as the backlash amount Lb.

[0072] When the rotation of motor 2 reverses and the drive teeth 12 move from an initial position A1 where they contact the driven teeth 22 of the first side Dr1 to an end position A2 where they contact the driven teeth 22 of the second side Dr2, the torque of motor 2 fluctuates in a special waveform. According to this embodiment, based on this special fluctuation of the torque of motor 2, the backlash time tb required for the drive teeth 12 to move from the initial position A1 to the end position A2 can be estimated. The product of the backlash time tb and the rotational speed vb of the drive gear 10 can then be estimated as the amount of backlash Lb between the drive gear 10 and the driven gear 20.

[0073] (2) The backlash estimation method of the second embodiment is the backlash estimation method of (1), wherein the reversal period tr includes a sudden change time trr1 in which the torque of the motor 2 changes rapidly, and the backlash time estimation step S3 estimates the time in which the torque of the motor 2 stabilizes immediately after the sudden change time trr1 as the backlash time tb.

[0074] During the time that the drive teeth 12 move from the initial position A1 to the final position A2, the resistance such as friction on the drive gear 10 decreases, and the torque of the motor 2 stabilizes. According to this embodiment, the backlash time tb can be easily estimated by estimating the time during which the torque of the motor 2 stabilizes as the backlash time tb.

[0075] (3) A third embodiment of the backlash estimation method is the backlash estimation method of (2), wherein the backlash time estimation step S3 includes: a torque time change rate acquisition step S11 which acquires the time change rate of the torque at each time by differentiating the torque acquired in the torque acquisition step S2 with respect to time; a peak detection step S13 which detects the first peak in the reversal period tr in the graph of the time change rate of the torque acquired in the torque time change rate acquisition step S11 as a first peak P1, and detects the first peak after the occurrence of the first peak P1 in the reversal period tr as a second peak P2; and a backlash time calculation step S14 which calculates the backlash time tb with the time of the first peak P1 or the time immediately after the first peak P1 as the start time tb1 of the backlash time tb, and the time of the second peak P2 or the time immediately before the second peak P2 as the end time tb2 of the backlash time tb.

[0076] According to this embodiment, the time during which the torque is stable can be calculated with high accuracy. Therefore, the backlash time tb can be calculated with high accuracy.

[0077] (4) A fourth embodiment of the backlash estimation method is the backlash estimation method of (3), wherein the backlash time estimation step S3 further includes a first filtering step S10 that removes a predetermined low-frequency noise from the torque acquired in the torque acquisition step S2, before the torque time rate change acquisition step S11.

[0078] This allows for the calculation of the torque rate of change over time by removing noise from the torque measurement. Therefore, the backlash time tb can be estimated with high accuracy based on the graph of the torque rate of change over time.

[0079] (5) A fifth embodiment of the backlash estimation method is a backlash estimation method of either (3) or (4), wherein the backlash time estimation step S3 further includes a second filtering step S12 after the peak detection step S13 for removing predetermined low-frequency noise from the torque time rate change acquired in the torque time rate change acquisition step S11.

[0080] According to this embodiment, noise can be removed from the rate of change of torque over time. This makes the first peak P1 and the second peak P2 clear. Therefore, the backlash time tb present between the first peak P1 and the second peak P2 can be estimated with high accuracy.

[0081] (6) The backlash estimation method of the sixth embodiment is any one of the backlash estimation methods of (3) to (5), wherein the backlash time calculation step S14 may calculate the backlash time tb by setting the start time tb1 of the backlash time tb as the time at which the rate of change of the torque becomes 0 for the first time immediately after the first peak P1, and the end time tb2 of the backlash time tb as the time at which the rate of change of the torque becomes 0 immediately before the second peak P2.

[0082] This clarifies the start time tb1 and end time tb2 of the backlash time tb. Therefore, the backlash time tb can be estimated more easily and with greater accuracy.

[0083] (7) The seventh embodiment of the backlash estimation method is any one of the backlash estimation methods from (1) to (6), which further includes a wear amount estimation step S5 for estimating the wear amount based on the backlash amount Lb estimated in the backlash amount estimation step S4.

[0084] The backlash amount Lb includes the amount of wear between the drive gear 10 and the driven gear 20 in addition to the backlash amount Lb before wear. In other words, the backlash amount Lb increases as the amount of wear increases. Therefore, according to this embodiment, the amount of wear can be easily estimated based on the estimated value of the backlash amount Lb.

[0085] (8) The program according to the eighth aspect is a program for estimating the amount of backlash Lb between a drive gear 10 driven by a motor 2 and a driven gear 20 that meshes with the drive gear 10, comprising: a motor drive step S1 in which the motor 2 is driven to rotate the drive gear 10 in the direction from the first side Dr1 to the second side Dr2, then reverses the rotation direction Dr of the drive gear 10, and rotates the drive gear 10 in the direction from the second side Dr2 to the first side Dr1; a torque acquisition step S2 in which the torque of the motor 2 is acquired during the reversal period tr in which the rotation direction Dr of the drive gear 10 is reversed; and the reverse Based on the torque of the motor 2 during the rotation period tr, the computer 1100 is instructed to perform a backlash time estimation step S3, which estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from an initial position A1 where it contacts the driven teeth 22 of the driven gear 20 located on the second side Dr2 to an end position A2 where it contacts the driven teeth 22 located on the first side Dr1, and a backlash amount estimation step S4, which estimates the product of the backlash time tb estimated in the backlash time estimation step S3 and the rotational speed vb of the drive gear 10 as the backlash amount Lb.

[0086] (9) A backlash estimation device 30 according to the ninth aspect is a backlash estimation device 30 that estimates the amount of backlash Lb between a drive gear 10 driven by a motor 2 and a driven gear 20 that meshes with the drive gear 10, comprising: a motor drive unit 31 that rotates the drive gear 10 in a direction from the first side Dr1 toward the second side Dr2, then reverses the rotation direction Dr of the drive gear 10 and drives the motor 2 to rotate the drive gear 10 in a direction from the second side Dr2 toward the first side Dr1; and a motor drive unit 31 that acquires the torque of the motor 2 during the reversal period tr in which the rotation direction Dr of the drive gear 10 is reversed. The system includes a torque acquisition unit 32, a backlash time estimation unit 40 that estimates the backlash time tb required for the drive teeth 12 of the drive gear 10 to move from an initial position A1 where it contacts the driven teeth 22 of the driven gear 20 located on the second side Dr2 to an end position A2 where it contacts the driven teeth 22 located on the first side Dr1, based on the torque of the motor 2 during the reversal period tr, and a backlash amount estimation unit 33 that estimates the product of the backlash time tb estimated by the backlash time estimation unit 40 and the rotational speed vb of the drive gear 10 as the backlash amount Lb. [Explanation of Symbols]

[0087] 1. Gear mechanism 2 motors 10 Drive Gear 11 Drive gear body 12 drive teeth 20 Driven gear 21 Driven gear body 22 Dependent teeth 30 Backlash Estimation Device 31 Motor drive unit 32 Torque acquisition unit 33 Backlash amount estimation unit 34 Wear amount estimation unit 40 Backlash time estimation unit 41 First filter section 42 Torque Time Change Rate Acquisition Unit 43 Second filter section 44 Peak detection unit 45 Backlash time calculation unit 1100 Computer 1110 processor 1120 Main Memory 1130 storage 1140 Interface A1 initial position A2 Final position Dr Rotation Direction Dr1 1st Dr2, second side Lb backlash amount P1 (First Peak) P2 (Second Peak) S1 Motor drive process S2 Torque acquisition process S3 Backlash time estimation process S4 Backlash amount estimation process S5 Wear amount estimation process S10 First filtering process S11 Torque Time Change Rate Acquisition Process S12 Second filtering process S13 Peak detection process S14 Backlash time calculation process tb backlash time tr Reversal Period tr1 Sudden change time tb1 start time tb2 end time

Claims

1. A backlash estimation method for estimating the amount of backlash between a drive gear driven by a motor and a driven gear that meshes with the drive gear, A motor driving step in which the motor is driven to rotate the drive gear in a direction from the first side toward the second side, and then reverse the direction of rotation of the drive gear so that the drive gear rotates in a direction from the second side toward the first side, A torque acquisition step is to acquire the torque of the motor during the reversal period in which the rotation direction of the drive gear is reversed, A backlash time estimation step, based on the torque of the motor during the reversal period, estimates the backlash time required for the drive teeth of the drive gear to move from an initial position where they contact the driven teeth of the driven gear located on the second side to an final position where they contact the driven teeth located on the first side. A backlash amount estimation step is performed to estimate the product of the backlash time estimated in the backlash time estimation step and the rotational speed of the drive gear as the backlash amount, A backlash estimation method that includes the following.

2. The aforementioned reversal period includes a rapid change period in which the torque of the motor changes abruptly. The backlash time estimation step estimates the time when the motor torque stabilizes immediately after the sudden change time as the backlash time. The backlash estimation method according to claim 1.

3. The aforementioned backlash time estimation process is: A torque time change rate acquisition step is performed by differentiating the torque acquired in the torque acquisition step with respect to time, thereby acquiring the time rate of change of the torque at each time point. A peak detection step in which, in the torque time rate change graph obtained in the torque time rate change acquisition step, the first peak within the reversal period is detected as the first peak, and the first peak after the occurrence of the first peak within the reversal period is detected as the second peak, A backlash time calculation step, in which the time of the first peak or the time immediately following the first peak is set as the start time of the backlash time, and the time of the second peak or the time immediately following the second peak is set as the end time of the backlash time, The backlash estimation method according to claim 2, which includes the following:

4. The aforementioned backlash time estimation process is: Prior to the torque time rate of change acquisition step, a first filtering step is further included to remove predetermined low-frequency noise from the torque acquired in the torque acquisition step. The backlash estimation method according to claim 3.

5. The aforementioned backlash time estimation process is: The process further includes a second filtering step after the peak detection step, which removes predetermined low-frequency noise from the torque time rate change acquired in the torque time rate change acquisition step. The backlash estimation method according to claim 3 or 4.

6. The backlash time calculation step involves setting the time at which the rate of change of the torque becomes zero for the first time immediately after the first peak as the start time of the backlash time, and the time at which the rate of change of the torque becomes zero immediately before the second peak as the end time of the backlash time, and calculating the backlash time. The backlash estimation method according to claim 3 or 4.

7. The process further includes a wear amount estimation step for estimating the wear amount based on the backlash amount estimated in the backlash amount estimation step, The backlash estimation method according to any one of claims 1 to 4.

8. A program for estimating the amount of backlash between a drive gear driven by a motor and a driven gear that meshes with the drive gear, A motor driving step in which the motor is driven to rotate the drive gear in a direction from the first side toward the second side, and then reverse the direction of rotation of the drive gear so that the drive gear rotates in a direction from the second side toward the first side, A torque acquisition step is to acquire the torque of the motor during the reversal period in which the rotation direction of the drive gear is reversed, A backlash time estimation step, based on the torque of the motor during the reversal period, estimates the backlash time required for the drive teeth of the drive gear to move from an initial position where they contact the driven teeth of the driven gear located on the second side to an final position where they contact the driven teeth located on the first side. A backlash amount estimation step is performed to estimate the product of the backlash time estimated in the backlash time estimation step and the rotational speed of the drive gear as the backlash amount, A program that causes a computer to execute something.

9. A backlash estimation device for estimating the amount of backlash between a drive gear driven by a motor and a driven gear that meshes with the drive gear, A motor drive unit that rotates the drive gear in a direction from the first side to the second side, then reverses the direction of rotation of the drive gear and drives the motor to rotate the drive gear in a direction from the second side to the first side, A torque acquisition unit that acquires the torque of the motor during the reversal period when the rotation direction of the drive gear is reversed, A backlash time estimation unit estimates the backlash time required for the drive teeth of the drive gear to move from an initial position where they contact the driven teeth of the driven gear located on the second side to an final position where they contact the driven teeth located on the first side, based on the torque of the motor during the reversal period. A backlash amount estimation unit estimates the product of the backlash time estimated by the backlash time estimation unit and the rotational speed of the drive gear as the backlash amount, A backlash estimation device equipped with the following features.

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